Field of the Invention
The invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device having partitions disposed in a color filter, and a method of forming the solid-state imaging device.
Description of the Related Art
Generally, solid-state imaging devices have a photoelectric transducer for converting light into electric charges, such as a charge coupled device (CCD), a metal oxide semiconductor (MOS) device, etc. Solid-state imaging devices have been used in various image-capturing apparatuses, for example video cameras, digital cameras, etc.
The solid-state imaging device may be a color solid-state imaging device, which has a color filter. In a conventional color solid-state imaging device, a primary-color filter consisting of a plurality of red (R), blue (B), and green (G) color filter portions is disposed over the light-receiving surface of two-dimensionally arranged photoelectric transducers provided on a semiconductor substrate. Each color filter portion of the primary-color filter corresponds to one photoelectric transducer.
In a conventional color filter, the red (R), blue (B), and green (G) color filter portions are adjacent together without gaps therebetween. However, light entering the color solid-state imaging device may be not perpendicular to the light-receiving surface of the two-dimensionally arranged photoelectric transducers. If light obliquely enters the light-receiving surface and passes through one color filter portion, the light will obliquely reach a photoelectric transducer corresponding to a color filter portion adjacent to the color filter portion which has the light passing through. As a result, color mixing occurs in solid-state imaging devices with a conventional color filter.
In order to avoid color mixing, a solid-state imaging device disclosed in U.S. Pat. No. 8,139,131 B2 provides a plurality of color filter segments mutually separated by interstices. The interstices contain a gas.
In order to avoid color mixing, a color-imaging device disclosed in U.S. Pat. No. 8,049,805 B2 provides a color filter including a plurality of coloring layers. Each of the coloring layers of the color filter include a side surface that is erected with respect to the surface of a semiconductor substrate, and an inclined surface that is continuous from the end of the side surface located on the opposite side of the semiconductor substrate toward the end portion of the coloring layer located on the opposite side of the semiconductor substrate. The coloring layers are arranged with their side surfaces being in contact with each other without a gap therebetween, and the end portion of the coloring layer has a curved surface.
Recently, the number of pixels of imaging devices has reached into the millions. The percentage of the area occupied by various wiring lines and electronic circuits required to operate each pixel is increased in each pixel with such advancements in high pixilation. As a result, the percentage of the area that can actually be utilized for the photoelectric transducers to receive light is decreased in each pixel. This means that the luminous sensitivity of the imaging device is reduced.
The above mentioned imaging devices provide a color filter to avoid color mixing, but the imaging devices do not provide a means to enhance the luminous sensitivity thereof, especially for a color filter containing white (W) color segments.